The field of the invention relates generally to spark igniters, and more specifically, to an apparatus and assembly for an extended life igniter assembly.
At least some known gas turbine engines include a spark igniter to facilitate engine starting and/or running. Such igniters are typically surface gap spark plugs in which a high energy spark discharge occurs between a center electrode and a ground electrode, traveling along the surface of an insulator. The spark discharge in such igniters is of the “high energy type” because of the nature of the ignition system used to cause sparking. The system includes a storage capacitor which is charged as the voltage applied thereto and across the igniter increases; when the applied voltage becomes sufficiently large to cause a spark discharge the electrical energy stored by the capacitor is discharged, flowing across the spark gap.
Electrode erosion has been a problem with spark igniters used with turbine engines for jet aircraft, sometimes constituting the limiting condition with respect to igniter life. Problem erosion of both the center electrode and the ground shell electrode occurs in igniters used with turbine engines. Conventional igniter ground electrodes are frequently made from Inconel® or from other conventional nickel alloys because they are relatively inexpensive. However, such electrodes may not provide the required service life in certain environments and duty cycles.